Preview: Qt 5.8 for AmigaOS 4.1

Alfkil T. Wennermark Announced on Amigans.net that he has started porting Qt 5.8 for AmigaOS 4.1 and AmigaOne computer systems. I will assume you have never used Qt before, and so will evaluate the different aspects of the Qt system. In the software development world, there are many tools and services available to help developers maximise their application development cycle, and squeeze every bit of functionality out of their products. These tools include compilers, debuggers, development environments, profilers, and, of course, graphical toolkits. Qt is rapidly growing in reputation and functionality’s, Qt is the flagship product from Norwegian company Trolltech and bought by Nokia in 2008, and Nokia is owned by Microsoft. Qt offers a slightly different method of creating graphical applications. First, Qt is a native toolkit. This means that when you create a Qt application and compile it, a native binary is created to run on each specific operating system. The speed implications for the application are therefore drastically improved, and large applications should work, theoretically, as fast as any other native software, with the added benefits of Qt’s cross platform source code. The actual cross platform nature of Qt is largely a feature of its Application Programming Interface (API). The concept here is that the source code remains the same for each platform version of Qt, so to create a binary for another platform, you just recompile using the Qt for that platform.

In addition to these graphical components, Qt includes a number of additional features. One of the most critical set of features are the convenience classes for handling data and types. Qt provides a number of these classes to support Arrays, Strings, Vectors, Maps, and many more types. In addition to these basic classes there are also classes to handle networking, sockets, file transfer, sound, and many other aspects of software development. It is good to see that Trolltech has created a rich API that not only provides graphical widgets, but also provides a number classes that make the day to day tasks of programming it a little bit easier. Qt is a C++ based toolkit, and Object Orientated Programming (OOP) is fundamental to using Qt. Each of the components is available as a class and each class has a number of methods to handle common tasks and features. Although some developers use procedural programming for graphical applications, the nature of OOP lends itself well to GUI programming due to the fact that inheritance is fundamental to GUI’s. One of the most interesting features of Qt is the way in which user interaction is handled. In many toolkits there is the concept of events, messages, call backs, etc., where a particular widget will start a particular event when the user does something. It is then the programmers responsibility to capture the event and do something constructive in response to it. Trolltech has taken this concept and refined it, coming up with a solution named Signals and Slots. The basic idea is that each class has a number of pre-defined signals that are emitted when something happens, such as clicking on a button or selecting an item in a menu.

Qt Designer essentially gives you the ability to draw your graphical interface visually by dropping interface elements onto a window. Qt Designer is a very flexible tool, and has support for all of the graphical widgets that are available in the toolkit. Not only can you add items such as buttons, checkboxes, radio buttons, scrollbars, textboxes, etc., but you can also add menus, and their items. Adding the components to your application window is as simple as selecting the widget from the toolbar and then drawing it. Qt Linguist is a tool for creating translations within Qt applications. The idea behind the tool is that you separate those who code the application from those who create translations. The traditional method of supporting multiple languages when developing software has been to implement multiple translations either within the code, or via a text file for each language. Qt prefers the more elegant technique of creating so called translation files that are created by the translators with Qt Linguist. Those files are then made use of by the developers in the Qt application. The final tool in the Qt toolbox is QMake. This simple little tool lets you handle the building your applications easily. Many developers spread their code out over multiple source files, and traditionally developers have needed to edit Makefiles, and other build scripts, to get their applications to build. When you roll in the multi-platform nature of Qt with different compilers and build environments, this could get real challenging real fast. QMake seeks to simplify the process, and when run will generate a make file for building your application. Qt is a great toolkit. I am impressed with the technical structure of the software, the feature set, and the documentation that is included. Qt seems to offer a nice combination of hard core power, and RAD development. C++ is a good choice for a language to base the toolkit on, although it would be nice to see bindings for Java, or possibly even PHP. The toolkit not only provides a good range of graphical components, but also provides high performance data handling classes, and nice additions, such as data aware database widgets and classes, OpenGL support, and other features. Coming soon for AmigaOS 4.1 and AmigaOne computers! Release TBA…